Tested and it works.

Michael Prokop <mika@grml.org> has uploaded a package that may fix your bug.
Please test the package and inform the maintainer whether
version 1.157.3-1grml.00 of live-initramfs works as intended or not.

Thank you

The changelog is attached below

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Hash: SHA1

Format: 1.8
Date: Sat, 05 Sep 2009 01:53:46 +0200
Source: live-initramfs
Binary: live-initramfs
Architecture: source all
Version: 1.157.3-1grml.00
Distribution: unstable
Urgency: low
Maintainer: Michael Prokop <mika@grml.org>
Changed-By: Michael Prokop <mika@grml.org>
Description: 
 live-initramfs - Debian Live initramfs hook
Changes: 
 live-initramfs (1.157.3-1grml.00) unstable; urgency=low
 .
   * Synchronise with Debian's version 1.157.3-1.
   * debian/patches/07_support_findiso.dpatch: insert a leading "/"
     in front of the FINDISO argument so it doesn't hit persons
     who forget a slash in the bootoption. Suggested by
     Philip Hands <phil@hands.com> - thanks!
   * grml/23networking: add support for bootoption noudev so the
     udev part in initramfs is skipped as well.
   * New patch 10_support_ethdevice.dpatch: support setting NIC name
     via ethdevice. Thanks to Helge Wagner! [Testing: issue724]
Checksums-Sha1: 
 ee7113c81b2c07ffd4e93081a09cddb80cdfc997 1276 live-initramfs_1.157.3-1grml.00.dsc
 253bae01efbfe6561b46669a108a3068bdb43675 95475 live-initramfs_1.157.3.orig.tar.gz
 4646e383d26cc99e5ac1a5fc0a405aabf65a174a 17888 live-initramfs_1.157.3-1grml.00.diff.gz
 1183fe18e404dad777e7547e9f6ae44ed7dc8c04 82740 live-initramfs_1.157.3-1grml.00_all.deb
Checksums-Sha256: 
 11d41e04983ae98b13578b23484e4f078defe2aa43b7a45ddac5faf138d5d792 1276 live-initramfs_1.157.3-1grml.00.dsc
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Files: 
 4b88bc468effeb751b9f53bf858a0e35 1276 misc optional live-initramfs_1.157.3-1grml.00.dsc
 c1cb8aa922070bfdff26c22b0d678497 95475 misc optional live-initramfs_1.157.3.orig.tar.gz
 4dc6090612c0673fd7ac748164ae9635 17888 misc optional live-initramfs_1.157.3-1grml.00.diff.gz
 bd4d455c5e4742de6616113dc591639a 82740 misc optional live-initramfs_1.157.3-1grml.00_all.deb

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Credits to Helge Wagner:

grml has configured the net boot to always use eth0 ("conf/initramfs.conf": 
"DEVICE=eth0"). I have changed the "scripts\live" file to include a 
configuration option for the "DEVICE" variable:

                        ethdevice=*)
                                DEVICE="${ARGUMENT#ethdevice=}"
                                export DEVICE
                                ;;
                                                                                                                                                                                  
So now i can add e.g. "ethdevice=eth3" to the command line in my pxe config 
file. I tried that and now my system is happy (using eth3 to connect to the nfs 
server).

Note by mika: already contacted live-initramfs upstream.